Analysis of the multisubunit exocyst complex in schizosaccharomyces pombe

Abstract

Cytokinesis in fission yeast Schizosaccharomyces pombe is achieved by the use of an actomyosin ring and the centripetal deposition of a division septum. Cleavage of the inner layer of the division septum results in the liberation of daughter cells. In this study, the essential role of a multi-protein complex exocyst in cell separation is described. Exocyst proteins localize to regions of active exocytosis and form a complex in vivo in S. pombe. Exocyst mutants appear to be able to elongate and assemble division septa, but are defective for cell separation. I therefore propose that the fission yeast exocyst may be involved in targeting of enzymes responsible for septum cleavage. The interaction of the exocyst with Rho3p, a member of the Rho family of small GTPase, suggesting that S. pombe Rho3p may regulate cell separation by modulating exocyst function.